A refrigerator is generally constructed of an inner box formed through vacuum molding, metal outer walls outside the inner box, wall surfaces surrounding three sides of a storeroom of the refrigerator with a urethane foam heat insulator injected and made to foam in a space formed between the inner box and the metal outer wall, and a door provided in an opening of the storeroom in a freely openable/closable manner with its interior also filled with a urethane foam heat insulator.
Furthermore, many electrical components such as various temperature sensors for detecting temperatures of various storerooms provided in the refrigerator and detecting completion of defrosting, a fan that blows air to the respective storerooms, a damper for adjusting the amount of cold air blow are arranged in the refrigerator and these electrical components are connected to a control substrate set up outside the refrigerator via lead wires.
Furthermore, the refrigerator uses heaters for temperature compensation inside the refrigerator, for prevention of condensation, for prevention of freezing, for defrosting or the like (e.g., see Patent Literature 1). These heaters are connected to the control substrate outside the refrigerator via lead wires in a heat insulating layer. Furthermore, the condensation prevention heater and storeroom temperature compensation heater are arranged on the urethane heat insulating layer side from the standpoint of securing an accommodation volume and safety such as preventing the heaters from contacting people.